Effect of ultra‐fine bubbles on capillary‐driven dye solution penetration in polyester–cotton fabrics

Abstract The influence of ultra‐fine bubbles (UFBs) on capillary‐driven dye solution penetration in polyester–cotton fabrics was investigated using a model dyeing system. Dye solutions were prepared with ultrapure water (UPW), UFB‐containing water and surfactant solutions, and penetration behaviour was evaluated from the dyed height developed in fabric specimens. For fabrics with fibres oriented perpendicular to the liquid surface, the dyed height obtained with UFB‐containing water was consistently greater than that obtained with UPW, reaching an increase of approximately 7% over the experimental period. In contrast, no significant difference was observed between surfactant solutions with and without UFBs. The influence of UFBs also depended on fabric orientation; when fabrics were cut at 45° relative to the liquid surface, the enhancement observed in the UPW system disappeared. Capillary rise experiments using glass tubes showed a similar tendency, with faster liquid rise in UFB‐containing water than in UPW. These results suggest that UFB‐containing liquids can influence dye solution penetration behaviour in textile substrates under specific conditions, particularly during the initial stage of liquid uptake. The findings provide experimental evidence of changes in capillary transport behaviour associated with UFB‐containing water. Further studies are required to assess the applicability of UFB‐containing liquids under practical dyeing conditions.